Method and apparatus to regulate oil pressure via controllable piston cooling jets

ABSTRACT

A method of regulating oil pressure within an engine assembly is provided. The engine assembly includes an oil pump configured to provide oil to an oil system of the engine assembly; a piston cooling jet configured to direct a jet of oil from the oil system towards a piston of an engine; and an electronic control valve configured to control the flow of oil to the piston cooling jet. The method includes operating the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or engine running speed; and regulating the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or engine running speed, by operating the electronic control valve.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to United Kingdom Application No. 1614465.1, filed Aug. 24, 2016. The entire contents of the above-referenced application are hereby incorporated by reference in its entirety for all purposes.

FIELD

The present disclosure relates to a method of regulating oil pressure within an engine assembly and is particularly, although not exclusively, concerned with a method of regulating oil pressure whilst reducing frictional losses within the engine assembly.

BACKGROUND/SUMMARY

In previous engine lubrication systems, solenoid valves have been employed to turn on and off cooling jets directed toward engine pistons. However, the piston cooling solenoids cannot be progressively adjusted to further regulate the flow oil cooling jets at intermediate flowrates between fully opened and closed configurations. Consequently, there may be a mismatch between the cooling jet flowrate and piston cooling requirements during certain operating conditions, thereby decreasing oil system operating efficiency. Attempts have been made to provide variable flow oil pumps to adjust the flowrate and pressure of the oil provided to the cooling jet nozzles. However, variable flow oil pumps may not only be costly but also inadvertently affect the flowrate of other lubrication system components, such as crankshaft lubrication jets. Therefore, in oil systems employing variable flow pumps, certain components may not achieve a desired amount of lubrication, thereby increasing the likelihood of component damage and decreasing component longevity.

To solve at least some of the aforementioned problems the inventors developed a method for regulating oil pressure in an engine assembly. The engine assembly includes an oil pump configured to provide oil to an oil system of the engine assembly, a piston cooling jet configured to direct a jet of oil from the oil system towards a piston of an engine, and an electronic control valve configured to control the flow of oil to the piston cooling jet. The method includes operating the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and regulating, e.g., actively controlling, the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the electronic control valve. In this way, the flowrate and/or oil pressure of the oil provided to the piston cooling jets may be fine-tuned based on engine operating conditions. As a result, oil system efficiency can be increased.

In one example, the electronic control valve may be operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil within the oil system is being regulated. Consequently, the efficiency of the oil system can be further increased.

In another example, the oil pump may be a fixed oil pump, e.g., a fixed geometry oil pump, configured such that the pressure of oil provided by the oil pump varies according to the engine running speed. In this way, the cost of the oil system may be reduced when compared to oil systems utilizing variable output oil pumps.

In yet another example, the electronic control valve may be a variable control valve configured to allow the flow rate of oil to the piston cooling jet to be selectively varied. In this way, the oil flow can be precisely adjusted to meet piston cooling requirements over a wide range of engine operating conditions.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a previously proposed engine assembly.

FIG. 2 is a schematic view of an oil system for the engine assembly according to the present disclosure.

FIG. 3 shows a method of operating an engine assembly according to arrangements of the present disclosure.

FIG. 4 shows another method for operating an engine assembly to control oil pressure delivered to a piston cooling jet.

DETAILED DESCRIPTION

With reference to prior art FIG. 1, a previously proposed engine assembly 1 for a motor vehicle comprises an oil system 2, a crank shaft 14 and a plurality of pistons 16 configured to reciprocate within a plurality of cylinders 18. The engine assembly 1 further comprises a valve train 20 comprising a plurality of inlet and outlet valves 22, 24 and a cam shaft 26.

The inlet and outlet valves 22, 24 are configured to control the flow of inlet and exhaust gases into and out of the cylinders 18, respectively. The cam shaft 26 is configured to control the operation of the inlet and outlet valves 22, 24.

The oil system 2 comprises an oil pump 4 configured to draw oil from an oil sump 6 via an oil pick-up 8 to an inlet 4 a of the oil pump. The oil pump may be driven by the engine. For example, as shown in FIG. 1, the oil pump 4 may be driven by the crank shaft 14 via a drive belt 5. The oil pick-up 8 may comprise a pick-up filter 8 a configured to reduce the amount of particles or debris drawn from the oil sump 6 into the oil system 2.

The oil pump 4 may be configured to pump a flow of oil through the oil system 2. The oil pump 4 may be a fixed oil pump for which the pressure increase delivered by the pump for a given flow rate is primarily dependent on the rotational speed of a shaft of the pump. Accordingly, the oil flow rate and/or outlet oil pressure supplied by the fixed oil pump may depend on the running speed of the engine.

The oil system 2 may further comprise an oil filter 10. The oil filter may receive oil from the oil pump 4. The oil filter 10 may be configured to filter the oil to reduce the quantity of particles present in the oil being pumped through the oil system 2.

Oil that passes through the oil filter 10 may enter an oil reservoir in which the pressurized oil is stored prior to being delivered to oil consuming components of the engine assembly 1. The reservoir may be a tank or chamber (not shown) provided between the oil pump 4 or the oil filter 10 and an oil duct 12. Alternatively, as shown in FIG. 1, no tank or chamber may be provided, and an initial portion of an oil duct 12 may form the oil reservoir. The oil duct 12 may be configured to deliver the oil to oil consuming components of the engine assembly 1.

The engine assembly 1 may comprise a plurality of journal bearings 27. The journal bearings may be configured to support portions 28 of the crank shaft 14 and may allow the crank shaft 14 to rotate relative to the engine assembly 1. Each of the journal bearings may comprise a journal bearing oil feed 28 a. Oil may flow through the oil feeds 28 a into each of the journal bearings and may lubricate the journal bearings to reduce friction between the portions 28 of the crank shaft 14 and the journal bearings.

The oil duct 12 may deliver oil from the oil system 2 to an oil channel 14 a provided in the crank shaft 14. The oil channel 14 a may be configured to allow oil to flow through the crank shaft 14 to the journal bearings oil feeds 28 a.

It may be desirable to deliver sufficient oil through the oil feeds 28 a, such that oil may coat substantially the full area of the journal bearings 27 that is in contact with the crank shaft 14. As the crank shaft 14 rotates, oil may be forced out of the journal bearings 27 and may drain through the engine assembly 1 to the oil sump 6. It may therefore be desirable for the oil system 2 to provide a flow, e.g., a continuous flow, of oil through the oil channel 14 a to the journal bearing oil feeds 28 a. The flow rate of oil consumed by the journal bearings 27 may vary according to the operating conditions of the engine assembly, e.g., the engine load, temperature and/or running speed.

As shown in FIG. 1, the engine assembly 1 may further comprise a plurality of piston cooling jets (PCJs) 30. Each of the piston cooling jets may be configured to direct a jet of oil onto a respective piston 16 of the engine assembly. Providing the jet of oil from the piston cooling jets 30 may cool and lubricate the pistons 16 and may increase the efficiency of the engine assembly 1. Use of the piston cooling jets 30 may be particularly beneficial when the engine is operating at a high running speed or under a high load.

The oil system 2 may comprise a PCJ valve 31 configured to control the flow of oil to the piston cooling jets 30. The PCJ valve 31 may be an electrically controlled valve, such as a solenoid valve, which is operable to open and close to selectively permit a flow of oil from the oil duct 12 to the PCJs 30. The electrically controlled PCJ valve may be coupled to a PCJ valve controller 40 or another controller of the vehicle, which only fully opens or fully closes the PCJ valve 31.

As mentioned above, the engine assembly 1 may comprise a cam shaft 26 configured to control the operation of the inlet and outlet valves 22, 24. The cam shaft may comprise a plurality of cams 26 a, that each act against a rocker (not shown) as the cam shaft 26 rotates. Each rocker may push against a valve stem 22 a, 24 a of a respective valve 22, 24 in order to open the valve and allow a flow of inlet or exhaust gases through the valve. The valves may each be provided with a spring 22 b, 24 b configured to return the valves to closed positions when not being pushed against by the rocker.

The cams 26 a may be configured such that, at particular points in the rotation of the cam shaft 26, respective ones of the cams are arranged to allow a corresponding valve 22, 24 to be closed. The cams 26 a may be configured such that when a valve 22, 24 is closed, a clearance gap is provided between the corresponding cam and rocker. This may allow the valve springs 22 b, 24 b to act to close the respective valves 22, 24 without the valve stems 22 a, 24 a interfering with the rockers or cams 26 a.

During operation of the engine assembly 1, the temperature of components of the engine assembly may vary, which may vary the size of the clearance gap. A lash adjustor, such as a hydraulic lash adjustor (not shown) may be provided at each of the rockers. The lash adjustor may be configured to adjust the size of the clearance gap, in order to allow the corresponding valve to close. The hydraulic lash adjustors may require a supply of oil in order to operate, and hence, the oil system 2, may be configured to supply oil to the hydraulic lash adjustors. The hydraulic lash adjustors may require oil to be supplied at high pressure, e.g., a higher pressure than the journal bearings 27. The flow rate of oil consumed by the hydraulic lash adjustors may vary according to the need to adjust the clearance gap.

The engine assembly 1 may comprise further oil consuming components, for example, as depicted in FIG. 1, the engine assembly 1 may comprise a variable valve timing system 32 configured to adjust the timings with which the inlet and/or outlet valves 22, 24 are opened and closed. Additionally or alternatively, the engine assembly 1 may comprise a turbocharger assembly 34, configured to increase the pressure of inlet air entering the cylinders 16 of the engine assembly 1 via the inlet valves 22. The turbocharger assembly 34 may receive one or more feeds of oil from the oil system 2, for example, the turbocharger may receive a high pressure oil feed and a low pressure oil feed. The flow rate of oil consumed by the turbocharger may depend on the operating conditions of the turbocharger assembly.

As mentioned above, each of the oil consuming components of the engine assembly 1 may have different requirements of pressure and flow rate of oil in order to operate most effectively. Furthermore, the flow rate of oil consumed by each of the oil consuming components may vary according to the current operating conditions of the engine, e.g., the engine running speed, power and/or heat output. For example, as described above, the oil system 2 may comprise a PCJ valve 31, that is configured to operate only in a fully open or a fully closed position. Thus, the PCJ valve 31 is a solenoid valve that can be only operated in a fully open or fully closed configuration.

As described above, the oil pump 4 may be a fixed oil pump, although the pressure and/or flow rate of oil provided by the fixed oil pump may vary according to the operating conditions of the engine, the operation of the fixed oil pump may vary differently to the oil consuming components. Hence, in some engine operating conditions, the oil pump 4 may supply a higher flow rate of oil and/or a higher pressure of oil than necessary to meet the requirements of each of the oil consuming components.

When the flow rate of oil being provided by the oil pump 4 is greater than the desired flow rate of oil being consumed by the components of the engine assembly, the pressure of oil within the oil duct 12 may increase. In some cases this may be undesirable as it may disrupt the operation of the oil pump and/or one or more of the oil consuming components.

In order to prevent the pressure of oil within the oil duct 12 reaching undesirable levels, the oil system includes a bleed valve 11. The bleed valve 11 may be connected between a position downstream of the oil pump 4 and drain into the oil sump 6. In the arrangement shown in FIG. 1, the bleed valve is coupled to the oil duct 12 downstream of the oil filter 10, however, it is equally envisaged that the bleed valve 11 may be connected to the oil system 2 between the oil pump 4 and the oil filter 10. The bleed valve 11 may be configured such that, if the pressure of oil within the oil reservoir or the oil duct 12 exceeds a first threshold pressure value, the bleed valve 11 opens, allowing oil to return to the oil sump 6. The bleed valve 11 may thereby be configured to maintain the pressure of oil at or below a first threshold pressure value.

Providing the bleed valve 11 within the engine assembly 1 may prevent the oil within the oil duct 12 or oil reservoir reaching undesirable levels. However, as the oil pump 4 continues operating whilst the bleed valve 11 is open, power may be drawn from the engine without providing any benefit to the engine assembly 1. In other words, power generated by the engine may be wasted.

In order to reduce the amount of power being drawn from the engine, the fixed oil pump 4 may be replaced by a variable oil pump. The variable oil pump may be configured to allow the pressure and/or flow rate of oil being output by the oil pump to be selectively varied. The variable oil pump may be controlled by a controller of the vehicle according to an oil requirement of the engine assembly. Hence, when it is desirable for the components of the engine to consume a low flow rate of oil, the variable oil pump may be controlled to reduce the pressure and/or flow rate of oil being provided by the oil pump. Providing a variable oil pump may therefore reduce the amount of oil being bled by the bleed valve 11, which may reduce the power from the engine being wasted.

Variable oil pumps may be more expensive than fixed oil pumps due to their increased complexity. Additionally, when the oil system is provided with a variable oil pump, it may be necessary for other components of the oil system to be configured for use together with the variable oil pump. This may significantly increase the cost of the oil system.

To increase the efficiency of the oil system a method for regulating oil pressure in an engine assembly has been developed by the inventors. The engine assembly may include an oil pump configured to provide oil to an oil system of the engine assembly; a piston cooling jet configured to direct a jet of oil from the oil system towards a piston of an engine; and an electronic control valve configured to control the flow of oil to the piston cooling jet. The method may include operating the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and regulating, e.g., actively controlling, the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the electronic control valve.

In one example, the electronic control valve may be operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil within the oil system is being regulated.

In another example, the oil pump may be a fixed oil pump, e.g., a fixed geometry oil pump, configured such that the pressure of oil provided by the oil pump varies according to the engine running speed.

In yet another example, the electronic control valve may be a variable control valve configured to allow the flow rate of oil to the piston cooling jet to be selectively varied.

In another example, the method may include determining the pressure of oil within the oil system, e.g., to be supplied from the oil system to the components of the engine assembly. The method may include controlling the operation of the electronic control valve such that the pressure of oil within the oil system is maintained at or below a first threshold pressure level, e.g., when the engine assembly is operating below the threshold power output or engine running speed. Additionally or alternatively, the method may include controlling the operation of the electronic control valve such that the pressure of oil within the oil system is not reduced below a second threshold pressure level.

In another example, the method may further include controlling the operation of the control valve to maintain the pressure of oil within the oil system at a particular value. The particular value may be fixed or varied, e.g., by a controller.

When the engine assembly is operating at or below the threshold power output or running speed, operating the control valve may be performed to regulate, e.g., actively control, the pressure of oil within the oil system, in some instances.

According to another aspect of the present disclosure, there is provided an engine assembly including: an oil pump configured to provide oil to an oil system; a piston cooling jet, configured to direct a jet of oil from the oil system towards a piston of an engine; an electronic control valve configured to control the flow of oil to the piston cooling jet; and a controller configured to: operate the control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and regulate the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the control valve.

In one example, the control valve may be operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil is being regulated.

In another example, the oil pump may be a fixed oil pump configured such that the pressure of oil provided by the pump varies according to a running speed of the engine assembly.

In yet another example, the control valve may be a variable flow control valve operable to control the flow rate of oil passing through the control valve.

In another example, the engine assembly may further include a pressure sensor configured to determine the pressure of oil within the oil system, e.g., to be supplied from the oil system to the components of the engine assembly.

In yet another example, the controller may be configured to control the operation of the control valve in order to maintain the pressure of oil within the oil system at or below a first threshold pressure level. Additionally or alternatively, the controller may be configured to control the operation of the control valve in order to maintain the pressure of oil within the oil system at or above a second threshold pressure level.

A vehicle, such as a motor vehicle, may include the above-mentioned engine assembly, in some instances.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

With reference to FIG. 2, in order to increase the efficiency of an engine assembly 50, without significantly increasing the cost of the engine assembly, if desired, the engine assembly 50 may be provided with an oil system 100 according to arrangements of the present disclosure.

Oil may be drawn from an oil sump 106 of the engine assembly 50 via an oil pick up 108 into an inlet 104 a of the oil pump 104. Oil pumped by the oil pump 104 may be output from an outlet 104 b of the oil pump to an oil reservoir in which the pressurized oil is stored prior to being delivered to oil consuming components of the engine assembly 50. The reservoir may be a tank or chamber (not shown) provided between the oil pump 104 and the oil duct 112. Alternatively, as shown in FIG. 2, the oil duct 112 may form the oil reservoir, e.g., there may be no tank or chamber. The oil system 100 may further comprise an oil filter 110. The oil filter 110 may be similar to the oil filter 10 described above with reference to FIG. 1.

The engine assembly 50 includes one or more piston cooling jets (PCJs) 130 configured to direct a jet of oil onto a respective piston of the engine assembly to cool and lubricate the targeted piston. The PCJs 130 may include nozzles generating a desired oil spray pattern, for instance. A piston cooling jetting (PCJ) valve 131 of the oil system 100 selectively controls the flow of oil to the piston cooling jets 130. The PCJ valve 131 may also be referred to as an electronic control valve. The PCJ valve 131 is configured to adjust the flowrate and pressure of the oil delivered to the PCJs 130. For example, the PCJ valve 131 may be operated in a fully opened position, where a maximum flowrate and/or pressure of oil is provided to the PCJs 130. The PCJ valve 131 may also be operated in a fully closed position where the flowrate of oil delivered to the PCJs 130 is substantially zero. Additionally, the PCJ valve 131 may also be operated in a plurality of intermediate positions between the fully closed and fully opened positions. For instance, the PCJ valve 131 may be operated to provider a target oil flowrate range between a maximum flowrate and minimum flowrate. For instance, the PCJ valve 131 may be continuously adjustable into a plurality of positions having varying oil flowrates and pressures. However, in other examples, the PCJ valve 131 may have a plurality of discrete positions between the fully opened and fully closed configurations.

The engine assembly 50 may further include one or more additional oil consuming components 132, such as journal bearings, a hydraulic lash adjustor, a turbocharger and/or any other component of the engine assembly 50.

The oil consuming components 132 and the PCJs 130 are included in an engine 150 having a cylinder 152. The engine 150 is configured to implement 4-stroke combustion cycles (i.e., intake, compression, power, and exhaust strokes) in the cylinder 152. Energy from the combustion process in the cylinder 152 may in-turn be transferred to a crankshaft 154.

An engine speed sensor 156 (e.g., hall effect sensor) is coupled to the crankshaft 154 and configured to generate an engine speed signal proportional to the speed of the engine. A pressure sensor 158 may also be included in the engine configured to generate a manifold absolute pressure (MAP) signal. Thus, the pressure sensor 158 may be coupled to an intake conduit such as an intake manifold. Additional sensors such as exhaust gas temperature sensors, oxygen sensors, etc., may also be included in the engine 150.

In the arrangement depicted in FIG. 2, the oil pump 104 is a fixed pressure oil pump configured to supply oil at a pressure and/or flow rate, which varies according to the speed of a shaft of the pump (which may be linked to engine running speed) and is not otherwise adjustable during use. In other words, the pressure increase delivered by the oil pump 104 at a particular flow rate of oil is primarily dependent on the rotational speed of the shaft of the pump and the pressure increase may not otherwise be actively controlled. As such, the pump may be a fixed geometry pump. As described above, at certain operating conditions of the engine assembly 50, the flow rate of oil being consumed by PCJs 130 and the further oil consuming components 132 may be less than the flow rate of oil being supplied by the oil pump 104. In this case, the pressure of oil within the oil reservoir and/or oil duct 112 may increase. However in other examples, the oil pump 104 may be a variable flow oil pump configured to adjust the pump's output flowrate.

In the arrangement described with reference to FIG. 1, the PCJ valve 31 is a solenoid valve configured to be either fully open or fully closed according to control signals from the PCJ valve controller 40. When the solenoid valve is opened, the flow rate of oil being supplied to the PCJs 30 may vary according to the pressure of oil within the oil reservoir. When the controller determines that cooling of the pistons is not desired, it may be undesirable to open the PCJ valve 31 to supply oil to the PCJs 30. For example, opening the PCJ valve 31 to allow oil to flow through the PCJs 30 may undesirably reduce the pressure of oil within the oil reservoir, which may be detrimental to the performance of the other oil consuming components of the engine assembly.

By contrast, in the arrangement shown in FIG. 2, the PCJ valve 131 is a variable valve, which may vary the degree to which the valve is opened and as such allows the flow rate and/or pressure of oil being supplied to the PCJs 130 to be selectively varied.

The PCJ valve 130 may be controlled by a PCJ controller 140. Thus, the PCJ controller 140 may send commands to the PCJ valve 130 to adjusting the valve into a fully open configuration, a fully closed configuration, and/or a plurality of intermediate positions. The PCJ controller 140 is shown FIG. 2 as a microcomputer, including microprocessor unit 142, input/output ports 144, an electronic storage medium for executable programs and calibration values shown as read-only memory chip 146 in this particular example, random access memory 148, keep alive memory 149, and a data bus.

Storage medium read-only memory 106 can be programmed with computer readable data representing instructions executable by processor 142 for performing the methods described below as well as other variants that are anticipated but not specifically listed. Exemplary methods are described with reference to FIGS. 3-4. The PCJ controller 140 may also receive signals from oil system sensors such as pressure sensor 136. Additional sensor signals that may be received by the PCJ controller 140 include a MAP signal from sensor 158 and a signal from engine speed sensor 156. Other sensor inputs that may be received by the PCJ controller 140 may include engine temperature, exhaust gas composition, exhaust gas temperature, throttle position, etc.

As another example, the controller may make a logical determination (e.g., regarding a configuration of the PCJ valve 131) based on logic rules that are a function of a degree of opening of the PCJ valve. The controller may then generate a control signal that is sent to actuators in the PCJ valve 131 for valve adjustment.

In one example, the degree of opening of the PCJ valve may be empirically determined and stored in a predetermined lookup tables or functions. For example, one table may correspond to different degrees of valve opening associated with different engine speeds and one table may correspond to different degree of valve openings associated with different engine loads. In another example, a single table may be used to correlate a degree of valve opening with both engine speed and engine load.

With reference to FIG. 3, PCJ controller 140 may control the operation of the PCJ valve 131 to supply oil to the PCJs 130 according to a method 300. The method 300 may be implemented by the oil system and PCJ controller 140 described above with regard to FIG. 2 to manage oil flow in the oil system. Instructions for carrying out method 300 and the remainder of the methods described herein may be executed by a controller based on instructions stored on a memory of the controller. The PCJ controller may employ actuators in the electronic oil control valve as well as other oil system components to implement the method.

The method 300 may begin at step 302, in which it is determined whether the engine running speed and/or power output is above a threshold, e.g., whether piston cooling by the PCJs is needed. An engine running speed threshold may be 3000, 2500, or 2000 revolutions per minute (RPM) for example. It will be appreciated that the thresholds described herein are non-zero positive values.

If the engine running speed and/or power output is above the threshold, the method 300 proceeds to step 304, in which the PCJ valve 131 is opened, e.g., fully opened, in order to supply a flow rate of oil to the PCJs 130. The oil may be ejected from the PCJs 130 at a flow rate that is above a threshold rate.

If the engine running speed and/or power output was found not to be above the threshold at step 302, e.g., if piston cooling may not be needed or decreased cooling is desired, the method 300, may proceed to step 306, in which the PCJ valve 131 is operated to supply oil to the PCJs to regulate the pressure of oil. For example, oil may be supplied to the PCJs at flow rate less than or equal to the threshold flow rate, e.g., by partially opening the PCJ valve 131.

Supplying at least a low flow rate of oil to the piston cooling jets 130 may be beneficial at most, e.g., substantially all, engine running conditions. The oil supplied may lubricate the movement of the pistons within their respective cylinders, which may reduce frictional losses within the engine assembly 50.

The PCJ controller 140 may be configured to control the flow rate of oil to the piston cooling jets 130 to regulate the pressure of oil within the oil system such that the pressure of oil within the oil reservoir does not increase above the first threshold pressure value. As supplying a low flow rate of oil to the piston cooling jets reduces frictional losses in the engine, regulating oil pressure in this way may be advantageous compared to bleeding oil back to the oil sump 106, for example using the bleed valve 11 shown in FIG. 1.

When the variable PCJ valve 131 is provided within the oil system 100 and configured to regulate the pressure of the oil system as described above, it may not be necessary to provide a bleed valve within the oil system 100. In other words, the oil system may be bled exclusively via the piston cooling jets 130. However, in some cases it may not be desirable to rely exclusively on the piston cooling jets. In this case, as shown in FIG. 2, the oil system 100 may include a bleed valve 134. In the arrangement shown in FIG. 2, the bleed valve 134 is connected downstream of the oil pump 104 at a position between the oil pump and the oil filter 110. However, it is equally envisaged that the bleed valve 134 may be connected downstream of the oil filter 110. For example, the bleed valve may be connected to the oil reservoir or the oil duct 112. However, in other examples, the bleed valve 134 may be omitted from the oil system 100.

As mentioned above, providing the low flow rate and/or pressure of oil to the piston cooling jets 130 may beneficially reduce frictional losses within the engine. Hence, it may be desirable to provide the low flow rate and/or pressure of oil to the PCJs 130 whenever the engine is operating at or below the threshold power output and/or running speed. However, it may be undesirable for the pressure of oil within the oil reservoir or oil duct 112, to be reduced below a second threshold pressure. Hence, when the pressure of oil within the oil reservoir is at or below the second threshold pressure, the PCJ valve 131 may be controlled to prevent a flow of oil to the PCJs 130. Specifically in one example, the PCJ valve 131 may be controlled to prevent a flow of oil to the PCJs 130 when oil demands in other lubricated components (e.g., journal bearing, lash adjuster, etc.,) is greater than a threshold value and/or when the engine speed is less than a threshold value.

The engine assembly 50 may include a pressure sensor 136 configured to determine the pressure of oil within the oil system. An oil pressure reading may be provided to the PCJ controller 140, which may control the operation of the PCJ valve 131 appropriately, e.g., in order to maintain the pressure within the oil system, e.g., within the oil reservoir, at or above the second threshold pressure. The method 300 may include an optional step 308, in which the pressure of oil within the system is determined and the opening position of the PCJ valve is adjusted accordingly. For example, the operation of the PCJ valve 131 may be adjusted to maintain the pressure of oil within the oil system at or close to a predetermined pressure. The optional step 308 may be performed as part of the third step 306. Alternatively, the optional step may be performed before and/or after the step 306.

The oil system 100 described above may be provided within the engine assembly 1 depicted in FIG. 1, e.g., the oil system 100 may be provided in place of the oil system 2. It is also envisaged that the oil system 100 may be provided within any other engine assembly.

FIG. 4 shows another method for managing oil pressure within an engine assembly including an oil system. The method 400 may be implemented by the oil system and engine assembly described above with regard to FIG. 2 to manage oil flow in the engine.

At 402 the method includes determining an engine running speed and/or engine load. For instance, signals from an engine speed sensor and/or manifold pressure sensor may be received by the PCJ controller. After the sensor signals are received, the PCJ controller ascertains the engine running speed and/or engine load.

At 404 the method determines if the engine running speed and/or engine load is greater than a threshold value. It will be appreciated that the threshold value is a non-zero value. For instance, the threshold value may be 1000 RPM.

If it is determined that the engine running speed and/or engine load is greater than the threshold value (YES at 404) the method advances to 406. At 406 the method includes fully opening the electronic control valve (e.g., PCJ valve). After 406 the method may return to 402. The electronic control valve is included in an oil system and selectively provides oil to at least one piston cooling jet. Additionally, the oil system includes an oil pump. In one instance, the oil pump may be a fixed geometry oil pump having an output that corresponds to engine speed. However in other examples, the oil pump may have an adjustable output.

On the other hand, if it is determined that the engine running speed and/or engine load is not greater than the threshold value (NO at 404) the method moves to step 408. At 408 the method includes determining a target oil pressure range based on the engine running speed and/or load. Next at 410 the method includes decreasing a degree of valve opening of the electronic control valve based on the target oil pressure range.

At 412 the method includes determining if an increase in engine speed and/or engine load has occurred. If it is determined that the engine speed and/or engine load has been increased (YES at 412) the method advances to 414. At 414 the method includes increasing a degree of valve opening of the electronic control valve.

On the other hand, if it is determined that the engine speed and/or engine load has not increased (NO at 414) the method advances to 415. At 415 the method includes maintaining the current electronic control valve position. At 416 the method includes determining if engine speed and/or engine load has decreased.

If it is determined that engine speed and/or engine load has decreased (YES at 416) the method includes at 418 further decreasing a degree of valve opening of the electronic control valve. Specifically in one example, the method may include adjusting the electronic control valve into a fully closed position when the engine speed and/or load drops below another threshold value (e.g., baseline threshold value).

However, if it is determined that engine speed and/or engine load has not decreased (NO at 416) the method advances to 419. At 419 the method includes maintaining the current electronic control valve position.

In additional examples, the electronic control valve may be adjusted based on lubrication needs of lubricated components other than the pistons. For instance, a lash adjuster may require additional oil pressure during certain operating conditions. In such an example, the degree of opening of the electronic control valve may be reduced to enable increased oil pressure to be provided to the lash adjuster. Therefore, in one example, the oil pressure provided to the PCJs from the PCJ valve may be decreased while the oil pressure provided to another lubricated component may be increased or vice-versa. The method 400 for regulating oil pressure in the engine assembly has the technical effect of decreasing losses in the engine assembly, thereby increasing the efficiency of the engine assembly.

The invention will further be described in the following paragraphs. In one aspect, a method of regulating oil pressure within an engine assembly is provided. The method includes operating an electronic control valve to provide a flow rate of oil above a threshold flow rate to a piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed, the piston cooling jet configured to jet of oil from an oil system towards a piston of the engine, the oil system including an oil pump; and regulating the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the control valve.

In another aspect, an engine assembly is provided. The engine assembly includes an oil pump configured to provide oil to an oil system; a piston cooling jet, configured to direct a jet of oil from the oil system towards a piston of the engine; an electronic control valve configured to control the flow of oil to the piston cooling jet; and a controller configured to: operate the control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and regulate the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the control valve.

In another aspect, a method for regulating oil pressure within an engine assembly is provided. The method includes operating an electronic control valve in a fully open position to provide oil to a piston cooling jet when the engine assembly is operating above a threshold engine running speed or engine load, the piston cooling jet configured to jet oil from an oil system towards a piston of an engine, the oil system including an oil pump; and decreasing a degree of valve opening of the electronic control valve to enable oil flow through the valve within a target pressure range to the piston cooling jet when the engine assembly is operating below the threshold engine running speed or load.

In any of the aspects or combinations of the aspects, the electronic control valve may be operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil within the oil system is being regulated.

In any of the aspects or combinations of the aspects, the oil pump may be a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to the engine running speed.

In any of the aspects or combinations of the aspects, the control valve may be a variable control valve configured to allow the flow rate of oil to the piston cooling jet to be selectively varied.

In any of the aspects or combinations of the aspects, the method may further include determining the pressure of oil within the oil system.

In any of the aspects or combinations of the aspects, the method may further include controlling the operation of the electronic control valve such that the pressure of oil within the oil system is maintained at or below a first threshold pressure level.

In any of the aspects or combinations of the aspects, the method may further include controlling the operation of the electronic control valve such that the pressure of oil within the oil system is not reduced below a second threshold pressure level.

In any of the aspects or combinations of the aspects, the method may further include controlling the operation of the electronic control valve to maintain the pressure of oil within the oil system at a particular value.

In any of the aspects or combinations of the aspects, the oil pump may be a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to a running speed of the engine assembly.

In any of the aspects or combinations of the aspects, the electronic control valve may be a variable flow control valve operable to control the flow rate of oil passing through the electronic control valve.

In any of the aspects or combinations of the aspects, the engine assembly may further include a pressure sensor configured to determine the pressure of oil within the oil system.

In any of the aspects or combinations of the aspects, the controller may be configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or below a first threshold pressure level.

In any of the aspects or combinations of the aspects, the controller may be configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or above a second threshold pressure level.

In any of the aspects or combinations of the aspects, the method may further include, subsequent to decreasing the degree of valve opening, increasing a degree of valve opening in response to determining an increase in engine speed or engine load.

In any of the aspects or combinations of the aspects, the oil pump may be a fixed geometry oil pump and where an output of the fixed geometry oil pump corresponds to the engine running speed.

In any of the aspects or combinations of the aspects, the method may further include operating the electronic control valve in a fully closed position.

In any of the aspects or combinations of the aspects, the method may further include, prior to decreasing the degree of valve opening, determining the target pressure range based on engine speed and engine load.

In any of the aspects or combinations of the aspects, the method may further include, the electronic control valve may be continuously adjustable in a plurality of open positions between the fully open position and a fully closed position.

It will be appreciated by those skilled in the art that although the invention has been described by way of example, with reference to one or more exemplary examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the invention as defined by the appended claims.

Note that the example control and estimation routines included herein can be used with various oil systems, engines, and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.

It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to other types of engines (V-6, 1-4, 1-6, V-12, opposed 4, etc.,), vehicle systems, etc. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

It will further be appreciated by those skilled in the art that although the invention has been described by way of example with reference to several embodiments it is not limited to the disclosed embodiments and that alternative embodiments could be constructed without departing from the scope of the invention as defined in the appended claims.

-   -   A method of regulating oil pressure within an engine assembly,         comprising:     -   operating an electronic control valve to provide a flow rate of         oil above a threshold flow rate to a piston cooling jet when the         engine assembly is operating above a threshold power output or         threshold engine running speed, the piston cooling jet         configured to jet of oil from an oil system towards a piston of         an engine, the oil system including an oil pump; and     -   regulating the pressure of oil within the oil system when the         engine assembly is operating below the threshold power output or         threshold engine running speed, by operating the electronic         control valve. 

2. The method of claim 1, wherein the electronic control valve is operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil within the oil system is being regulated.
 3. The method of claim 1, wherein the oil pump is a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to the engine running speed.
 4. The method of claim 1, wherein the electronic control valve is a variable control valve configured to allow the flow rate of oil to the piston cooling jet to be selectively varied.
 5. The method of claim 1, further comprising determining the pressure of oil within the oil system.
 6. The method of claim 1, further comprising: controlling the operation of the electronic control valve such that the pressure of oil within the oil system is maintained at or below a first threshold pressure level.
 7. The method of claim 6, further comprising: controlling the operation of the electronic control valve such that the pressure of oil within the oil system is not reduced below a second threshold pressure level.
 8. The method of claim 1, further comprising: controlling the operation of the electronic control valve to maintain the pressure of oil within the oil system at a particular value.
 9. An engine assembly, comprising: an oil pump configured to provide oil to an oil system; a piston cooling jet, configured to direct a jet of oil from the oil system towards a piston of an engine; an electronic control valve configured to control the flow of oil to the piston cooling jet; and a controller configured to: operate the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and regulate the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the electronic control valve.
 10. The engine assembly of claim 9, wherein the oil pump is a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to a running speed of the engine assembly.
 11. The engine assembly of claim 9, wherein the electronic control valve is a variable flow control valve operable to control the flow rate of oil passing through the electronic control valve.
 12. The engine assembly of claim 11, wherein the engine assembly further comprises a pressure sensor configured to determine the pressure of oil within the oil system.
 13. The engine assembly of claim 12, wherein the controller is configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or below a first threshold pressure level.
 14. The engine assembly of claim 13, wherein the controller is configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or above a second threshold pressure level.
 15. A method for regulating oil pressure within an engine assembly, comprising: operating an electronic control valve in a fully open position to provide oil to a piston cooling jet when the engine assembly is operating above a threshold engine running speed or engine load, the piston cooling jet configured to jet oil from an oil system towards a piston of an engine, the oil system including an oil pump; and decreasing a degree of valve opening of the electronic control valve to enable oil flow through the valve within a target pressure range to the piston cooling jet when the engine assembly is operating below the threshold engine running speed or load.
 16. The method of claim 15, further comprising, subsequent to decreasing the degree of valve opening, increasing a degree of valve opening in response to determining an increase in engine speed or engine load.
 17. The method of claim 15, where the oil pump is a fixed geometry oil pump and where an output of the fixed geometry oil pump corresponds to the engine running speed.
 18. The method of claim 15, further comprising, operating the electronic control valve in a fully closed position.
 19. The method of claim 15, further comprising, prior to decreasing the degree of valve opening, determining the target pressure range based on engine speed and engine load.
 20. The method of claim 15, where the electronic control valve is continuously adjustable in a plurality of open positions between the fully open position and a fully closed position. 